America's usual tack on Iran's nuclear program hasn't worked. The US should test the intentions of Iran's new President Hasan Rouhani, who visits the UN today, by trying a new approach: capitalizing on areas where US and Iranian interests align, such as Afghanistan, or even Iraq.

Iranian President Hasan Rouhani speaks during an interview with state television in Tehran Sept. 10. Mr. Rouhani visits the United Nations today. Op-ed contributors, Ambs. Peter Jenkins and Robert Hunter write: '[T]he US should understand that calling for more sanctions (as Congress has done) in the face of possible change by Iran under its new president poisons diplomacy before it starts.'

Washington, D.C.; and Bath, England — The visit of Iran's new President Hasan Rouhani to the United Nations today helps mark his return to the diplomatic frontline, along with Iran's new foreign minister, Javad Zarif. Their reemergence has raised hopes that Western concerns over Iran’s nuclear program might at last be allayed. Both men are Western-educated and understand American ways; both have proved to be tough but pragmatic diplomats.

Yet even before Mr. Rouhani took office, skeptics doubted that the US would exercise the imagination and flexibility needed for diplomacy to succeed and to reduce risks of a conflict that can benefit no one.

Their doubts aren’t unfounded. But instead of sticking to the usual demands and arguments, which has proved to be a sterile pursuit, the United States should test the intentions of Team Rouhani by trying a new approach. If the US genuinely wants only to keep Iran from getting a nuclear bomb, Washington needs to seek and leverage areas of common – or at least compatible – interests.

Hardliners suggest that the US should insist that Iran limit its uranium enrichment capability to just a few thousand first-generation centrifuge machines. At such a level of capacity, there would be minimal risk of Iran’s producing enough highly-enriched uranium for a nuclear weapon without being detected in good time.

But there is no reason to think that Iran will agree to such limits on uranium enrichment. Tehran says it has a practical need for many more than a few thousand machines – to produce fuel for power-generating reactors. Not unreasonably, Iran also asserts the principle of equal treatment for all parties to the Nuclear Non-Proliferation Treaty to which it belongs.

America’s asserting that Iran’s non-compliance with the treaty has lost it the right to operate enrichment plants has gotten us nowhere for more than a decade and it won’t work now.

Absent from the treaty is any indication that parties who stray forfeit their treaty right to make peaceful use of nuclear fuel-cycle technologies. Further, many states, including Russia and China whose full cooperation is required to make sanctions work, argue that Iran has been compliant with the non-proliferation treaty since the International Atomic Energy Agency reported that all Iran’s pre-2004 safeguards failures had been corrected.

Instead of re-litigating the treaty, Washington must take a new tack and gauge the extent to which Rouhani – and the supreme leader – are truly willing to work on a diplomatic solution.

Iran recognizes that its failure to comply with nuclear safeguards obligations forfeited the confidence of the international community in Iranian intentions.

So even during the bleak years when Rouhani and Mr. Zarif, now his foreign minister, were side-lined, Iranian representatives signaled their readiness to volunteer temporary confidence-building restrictions to the scope of their enrichment activity: an end to production of uranium enriched to 19.75 percent, for instance, and disposal abroad of stocks of 19.75 percent material in return for research reactor fuel.

That past readiness to volunteer confidence-building measures during a transition to full enjoyment of treaty rights can be explored.

The Obama administration should also recall that for years the national intelligence community has been advising it to guard against an Iranian “break-out” by influencing the cost/benefit calculations – the strategic calculus – of Iran’s decisionmakers. Iranian recognition that they have much to lose by breaking out, and little to gain, is the most effective counter-proliferation bulwark imaginable.

Assuming that Iran wants to avoid the spread of nuclear weapons to nearby states and its own further isolation, both regionally and internationally, its interest is to keep the non-proliferation treaty intact and strike a reasonable deal if the US will offer one.

Like other successful arms control instruments, the Nuclear Non-Proliferation Treaty is built on a principle that saved the US tens of billions of dollars during the cold war and paved the way for its end: build an agreement on each party’s self-interest, and then verify each is upholding the deal.

Requiring Iran to subject itself to intrusive verification measures, as the US did of the Soviet Union (and vice versa), goes with the grain of the treaty. Trying to circumscribe the development of nuclear technologies for peaceful purposes does not, and can be a deal breaker.

Finally, the US should understand that calling for more sanctions (as Congress has done) in the face of possible change by Iran under its new president poisons diplomacy before it starts.

Instead, the US must use areas where US and Iranian interests align – such as in Afghanistan and maybe Iraq, certainly in freedom of shipping through the Strait of Hormuz – to bring the two countries together. America did this with the Soviet Union even at the height of the cold war. To act as though Iran is necessarily America’s implacable foe profits no one, kills the chances for diplomacy, and even increases risk of conflict.

Peter Jenkins was British Ambassador to the IAEA from 2001 to 2006 (and played a part in the European Union negotiations with Rouhani and Zarif between 2003 and 2005). He is now a partner in The Ambassador Partnership, an international corporate-diplomacy consulting group.

Robert Hunter was US Ambassador to NATO from 1993 to 1997 and was in charge of Middle East issues in the Carter white house.